The present invention relates to improvements in or relating to a coil device used as a line filter for controlling an electromagnetic noise occurring in, for example, an electronic equipment and passing into a transmission line, or an electromagnetic noise entering the electronic equipment through the transmission line.
A conventional coil device 100 is of such a constitution as shown in FIGS. 1 and 2 for example. Winding a coil 130 is performed with the starting end S of the wiring first wound several turns in first to third reserve wire grooves formed in both collars 121 and a center collar 122 of a two-split bobbin 120. After winding, the last end E of the winding on each coil 130 is fastened in second and fourth reserve wire grooves 123b and 123d or tacked with an adhesive on the outer periphery of each coil 130. Then, after the coiled bobbin 120 is mounted on a bobbin holding base 140, the starting end S and the last end E of the winding are loosened off from the reserve wire grooves 123a and 123c and from the tacked points on the outer periphery of the coil, then connected to corresponding lead terminals 141, and finally soldered thereto. The conventional coil device, therefore, has the following problems.
(A) The conventional coil device requires such complicated operations as winding and unwinding the starting end of the coil winding in the reserve wire grooves 123a and 123c of each coil 130, and tacking the last end E of the coil winding to, and detaching it from, the outer periphery of the coil 130 and 130. This coil device, therefore, is not suitable for coil winding operation by the use of automated machinery.
(B) When the starting end S of each coil winding is released from each of the reserve wire groove 123a and 123c and also when the last end E of the winding is detached from the outer peripheral section of the coil 130, each winding end is not necessarily extended straight. In addition, because the mounting of a combination of a core 110 and a bobbin 12 is accompanied with vibration at each wiring end, holding by fingers to fasten the starting end S and the last end E to the lead terminals 141 of the base 140 is also not suitable for automatic processing.